I am trying read traffic from a couple of test mobile devices, iphones, androids etc. I've done this for over a year using primarily Fiddler but also Charles. I did it up until yesterday without any issue. But today the devices do not appear to be connecting to my computer. I have confirmed that everything is configured right eg. device is set to use my computer as a proxy after I put in my computers IP address that I got by doing a simple ipconfig, sorry if this all sounds redundant but just letting you know my steps, better to have more information than less. I also turned off my firewall no change.
I thought perhaps something was done to our network, but I installed Fiddler on a coworkers computer and was able to proxy into that computer without any issue. Confirmed all drivers are up to date and really there was no change between yesterday and today except a deep scan with Malwarebites. Frankly sort of at a loss for what it might be, I have reinstalled Fiddler on my computer (the primary one I use, didn't reinstall Charles cause I don't want to deal with license issue right now) but at same time what are the chances that both stopped working at same time.
There's a high likelihood that your PC's firewall is blocking the inbound connection. You should check your firewall configuration to see if it's configured to allow inbound connections to Fiddler.
On your Fiddler-running PC, ensure Tools > Fiddler Options > Connections > Allow Remote Computers to connect is checked (if not, check it and restart).
From your co-worker's PC, try visiting
http://<FiddlerPCName>:8888/in the browser. Does the traffic appear in Fiddler?